In Shemos 25:1-27:21 (all of Terumah and the very beginning of Tetzaveh), the Pesukim describe the vessels of the Mishkan, the structure of the Mishkan, and the oil of the Menorah.
In Shemos 28:1-29:46 (the bulk of Tetzaveh), the Pesukim describe the clothing of the Kohanim and the process to consecrate them.
In 30:1-31:11 (Shevi’i of Tetzaveh and Rishon of Ki Sisa), the Pesukim return to the topic of Mishkan vessels and function.
Why are they broken up this way? Why isn’t the middle passage about the Kohanim either at the beginning or at the end, instead of breaking up the Mishkan into two parts?